Fuel flowing through a fuel injector typically exits at a nozzle end of the fuel injector. The nozzle end is believed to have a disk with at least one orifice to control, in part, the spray pattern and the direction of the fuel exiting the fuel injector.
The orifice used in fuel injectors is believed to be formed by drilling through a workpiece that can be of a suitable cross section. The work piece is believed to be further machined so that the work piece can be assembled with the nozzle end of a fuel injector.
At least two laser-machining techniques are believed to be used for machining orifices. One is percussion drilling, and the other is trepanning or helical drilling. Percussion drilling is believed to be less than desirable due to a variation in beam profile and targeting or the random nature of metal heating and expulsion that most likely result in a non-cylindrical or non-circular orifice. Trepanning, on the other hand, is believed to be more precise as a center hole is believed to be initially formed before the formation of the orifice and is believed to create less debris during machining. Helical drilling is similar to trepanning but without the initial formation of a center hole.
Regardless of the techniques, a single laser is typically used to machine a single work piece at a time in such laser system. In order to maximize the use of the laser system, it would be desirable to increase the ability to form more than one orifice at a time on a single work piece or to form orifices on more than one work piece at a time. It would also be desirable to increase the number of consistent quality orifices produced by a single laser machining system.
The present invention provides for at least one method of generating multiple focus spots on a work piece by a single laser light source in a laser system. The laser light source has a laser beam extending along a beam axis that intersects with a work piece. The work piece has a first surface spaced from a second surface at between 50 to 600 microns. In one preferred embodiment of the invention, the method can be achieved, in part, by directing a first perimeter of the laser beam to a first position on at least one of the surfaces of the work piece at a first power density sufficient to machine materials on the work piece between the first and second surfaces; and redirecting a portion of the laser beam within the first perimeter that forms a second perimeter to a second position on the at least one surface of the work piece at a second power density sufficient to machine materials on the work piece between the first and second surfaces.